Molecular dynamics simulation of DNA sequencing through a graphene nanopore.
Cytosine molecules (white) linked to nanopore detect guanine (green) in vertical
DNA strand. Inset shows graphene deflection over time.
Credit: T.A. Wassenaar/Univ. Groningen; A.F. Kazakov and A. Smolyanitsky/NIST.
(January 15, 2016) Researchers at the National Institute of Standards and Technology (NIST) have simulated a new concept for rapid, accurate gene sequencing by pulling a DNA molecule through a tiny, chemically activated hole in graphene—an ultrathin sheet of carbon atoms—and detecting changes in electrical current.
The NIST study suggests the method could identify about 66 billion bases—the smallest units of genetic information—per second with 90 percent accuracy and no false positives. If demonstrated experimentally, the NIST method might ultimately be faster and cheaper than conventional DNA sequencing, meeting a critical need for applications such as forensics.
Conventional sequencing, developed in the 1970s, involves separating, copying, labeling and reassembling pieces of DNA to read the genetic information. The new NIST proposal is a twist on the more recent “nanopore sequencing” idea of pulling DNA through a hole in specific materials, originally a protein. This concept—pioneered 20 years ago at NIST—is based on the passage of electrically charged particles (ions) through the pore. The idea remains popular but poses challenges such as unwanted electrical noise, or interference, and inadequate selectivity.
By contrast, NIST’s new proposal is to create temporary chemical bonds and rely on graphene’s capability to convert the mechanical strains from breaking those bonds into measurable blips in electrical current.
"This is essentially a tiny strain sensor,” says NIST theorist Alex Smolyanitsky, who came up with the idea and led the project. “We did not invent a complete technology. We outlined a new physical principle that can potentially be far superior to anything else out there.”